Referring to CV2269 datasheet:
If we do not connect anything to the grid we leave it at space potential. The grid current is 0. If it were not zero there would be current accumulation and change of potential of the grid. We are at steady state for given conditions, ie cathode temperature etc.
If we make the grid more negative than space potential then valve datasheets show very very small current in reverse direction. Is this coming from the grid attracting positive ions?
How would the CV2269 sound like with open grid powered by 9V at the plate on the Pleiadss V6 schematic:
Would it also do automatic gain control as the tiny grid current that flows when signal is applied is asymmetrical between negative and positive signal excursion.
Would large mic signals progressively make the grid attract more electron getting more and more negative ie gain decreasing?
Would then a say 60MΩ resistor from grid to the same open grid potential provide a compressor release time? Would a potentiometer across a cathode resistor or across a voltage source allow us to find the exact same potemtial where no click sound is heard by connecting or disconecting the grid leak resistor (no change is anode current)? (Ear protection should always be used on such sensitive circuits).
This compression technique seems to be used on the Neumann U47 V14 amplifier, see previous posts.
See also one of the best ever papers written on electron tubes by the master himself, Armstrong, inventor of FM radio.
Operating features of the Audion - E. H. Armstrong
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